Brussels — It is a classic case of doves vs. hawks. The behind-the-scenes debate among Iran's political, religious, and military leaders centers on strategy in the nearly four-year-old war with Iraq.
The nation's ruling clergymen, says a usually well-informed source contacted in Tehran, agree on some basics: that Iraq's secular regime must be detroyed; and that, although Iranian leaders publicly reject any compromise with Iraqi President Saddam Hussein, Iranian fighters probably will never beat the Iraqi Army.
Also, the Tehran source says, most Iranian leaders feel that Iran now confronts a coalition of conservative Arab countries backed by both superpowers and France.
The disagreement arises over how to handle this new situation. There appear to be three schools of thought among the leaders:
* The ''hawks'' believes that Iran should launch its long-expected ground offensive into Iraq as the only way to end the war. The aim of such a move would be either to surround the southern port of Basra or to bring Iranian fighters within shelling range of Baghdad, the capital. The hawks argue that only a clear-cut Iraqi defeat could force President Hussein out of power.
* Another group holds that the risk of failure in such an offensive is too high. They say Iranian fighters should remain entrenched in their positions on Iraq's border and maintain pressure on the Iraqi Army.
At the same time, they say, the Iranian government should encourage Iraqi dissidents within Iraq to step up their activities against Hussein's regime. Defenders of this strategy are convinced that a land offensive would help Hussein by reinforcing national unity in Iraq.
* A third but tiny group wants Iran to ask Algeria to act as a mediator. These ''doves'' contend that Saudi Arabia and its Persian Gulf allies are ready to pay Iran huge sums as war reparations.
According to an Iranian diplomat contacted in Paris, the leading proponents of an offensive are Iranian leader Ayatollah Khomeini and the speaker of the parliament, Hojatolislam Hashemi Rafsanjani.
The offensive's leading opponent is Iranian President Ali Khamenei, the diplomat says. President Khamenei, he says, is concerned by the high number of casualties such a battle would involve. Prime Minister Hossein Mussavi, who supports Khamenei, sees the war as an obstacle to his program of economic and social reforms.
''President Khamenei,'' the Iranian envoy continues, ''was also upset by the conversation he had on May 24 with Syrian Vice-President Abdel Halim Khaddam.''
Mr. Khaddam reportedly told Khamenei that Syria would not accept the establishment of an Islamic republic in Iraq and that Syria might withdraw its support for Iran if the Iranians were to escalate the war.
''Khamenei has also been influenced by reports from Iranian Revolutionary Guards and Army officers explaining that the Iraqi soldiers would (use) large antitank ditches and wide mine fields interspersed with radar-guided automatic machine guns,'' the envoy continues.
Western diplomats in Tehran believe that Ayatollah Khomeini will soon intervene in the debate. Based on his record of intransigence, Khomeini is unlikely to openly accept a compromise. But, to preserve the unity of his regime , he may refer the problem to the parliament.
There are rumors in Tehran that several members of parliament have privately voiced concern about the human and economic costs of the war. Those deputies are said to fear that a new, bloody offensive might spawn social disturbances in their constituencies.